I am  using parachute cord for all of my rope.  I used the everlast #70 pulley. You can see a picture here.
  (You need to Login or Register  I use about 7 inch of ½ inch PVC pipe between the two top pulleys.  Today was the first day I put it up and lifted any thing.  I only had about 35 lb hanging from it but it worked well.  Care must be taken when putting it up  and taking it down to keep from tangling the ropes. If one of the ropes was a different color it would make it easer to set up. If you let the rope roll over the side of the pulley it will get pinched between the side and the wheel.  These pulleys roll very easy and will more than hold the weight and once every thing is straight and you have weight on then they stay straight but having the rope pinched over the edge of the pulley should be avoided.